WTB - do any of you enthusiasts have your stock exhaust taking up space? I will take it off your hands!
I want to do the oem exhaust mod, but need to be able to put the stock exhaust back at the end of the lease

Just do the mod to yours and when it comes to lease-end just swap with somebody else. You could even charge a couple hundred bucks for the swap EASY. No point in having one laying around for a long time period, like 2nd poster ^ already mentioned, you can't break it down so it's a pain in the ass.